Photographic bleach compositions

ABSTRACT

The incorporation of bromate ion into photographic bleach compositions which include trivalent iron complexes of aminopolycarboxylic acid as the bleaching agent inhibits the formation of leuco cyan dyes when these bleaches are used in the processing of incorporated coupler reversal emulsions.

Unite States Patent [1 1 Brugger et al.

[ Nov. 6, 1973 PHOTOGRAPHIC BLEACH COMPOSITIONS [76] Inventors: DonaldJ. Brugger; Barry R.

Hagenbuch, both of 1669 Lake Ave., Rochester, NY. 14650 221 Filed: Apr.6, 1972 211 Appl. No.: 241,592

[52] US. Cl 96/60 R, 96/22, 96/59 [51] Int. Cl. G03c 5/32, G036 7/16,G030 5/50 [58] Field of Search 96/60, 60BF, 59,

[56] References Cited UNITED STATES PATENTS 4/1934 Gaspar 96/21 9/1952DENSITY Zappert 96/50:

2,611,700 9/1952 Brunncr et al v. 96/60 FOREIGN PATENTS OR APPLICATIONS580,359 7/1959 Canada 96/60 R Primary Examiner-Norman G. TorchinAssistant ExaminerM. F. Kelley Att0rney-William T. French et al.

[ 7 ABSTRACT The incorporation of bromate ion into photographic bleachcompositions which include trivalent iron complexes ofaminopolycarboxylic acid as the bleaching agent inhibits the formationof Ieuco cyan dyes when these bleaches are used in the processing ofincorpo rated coupler reversal emulsions.

1'2 Claims, 1 Drawing Figure LOG-E PHOTOGRAPIIIC BLEACH COMPOSITIONSThis invention relates in general't'o photographic processing and inparticular to bleach solutions which include bromate ion.

BACKGROUND OF THE INVENTION:

U. S. Patent Application Ser. No. 228,386 filed Feb. 22, 1972 andentitled Photographic Bleach Compositions describes novel bleachcompositions comprising as the bleaching agent a trivalent iron complexof an aminopolycarboxylicacid and halide ion as a silver solvent whichhastens conversion of oxidized silver to silver halide therebyfacilitating recovery of the silver using electrolytic techniques bymaking the silver available for complexing with a fixing agent in asubsequent fixing bath which is free of iron. The iron present in" acombined bleach and fix bath apparently hinders the recovery of silverfrom the spent fixing solution when electrolytic techniques are used.

Bleach baths of the foregoing type are extremely useful and permitexceptionally high yields of recovered vention, the bleach compositionincludes between about 8 and 30 grams per liter of sodium bromate. ThepH of the bleach solution should be maintained between about 2 and 8preferably between about 4 and 6.5 and ideally at a level of 5 i- .5.

The trivalent iron salts of the following aminopolycarboxylic acids arerepresentative of those useful in the bleach solutions containing iodideor bromide salts,

nitrilotriacetic acid,

ethylenediamine tetraacetic acid, ethyliminodipropionic acid,diethylenetriamine pentaacetic acid, ortho-diamine cyclohexanetetraacetic acid,

ethylene glycol bis(aminoethyl ether) tetraacetic acid,

diaminopropanol tetraacetic acid, N-(2-hydroxyethyl)ethylenediam-inetriacetic acid, and the like. I 4 British Pat. No. 1,200,188 may bereferred to for additional aminopolycarboxylic acids useful in theprocess of the invention. The ferric salts'of aminopolycarboxylic acidsutilized in the practice of this'invention may silver, however, they dopossess one rather significant drawback which may be significant in themachine processing of incorporated coupler reversal products. Thisdrawback is that these bleaching agents tend to form leuco cyandyes inthese materials. These leuco dyes can be oxidized back to photographicdyes, however, this procedure requires an extended bleaching treatmentof the type which cannot readily be achieved under the stringentlimitations of time present in a machine process. I

BRIEF DESCRIPTION OF THE INVENTION:

It has now been discovered that theincorporation of bromate ion as analkali metal or ammonium bromate salt into bleaches containing ferriccomplexes of aminopolycarboxylic acids eliminates the problem of leucodye formation by causing oxidation of the leuco dye to photographicdye'within the time generally required for bleaching.

DETAILEDDESCRIPTION OF THE INVENTION:

from about 50 to about 350 grams per liter of an alkali metal orammonium bromide or from about 1 upv to about 350 grams per liter ofalkali metal or ammonium iodide. As should be obvious, however, mixturesof bromide and iodide salts may also be used to achieve suitable resultsin the application of these solu-tions to specific incorporated couplerreversal photographic materials. According to the present invention theproblem of incipient leuco dye formation which can occur with the use ofthese bleaches in machine processing or where only brief bleachingperiods on the order of less than about three minutes are availablecan'be eliminated by including in the bleach from about 5 to about 50grams per liter of alkali metal or ammonium bromate. According to apreferred embodiment of the inbe salts in which all cations are theferric ion or salts in which one or, more of the carboxyl groups haveformed a salt with a cation other than iron, e.g'. with ammonia or'withan alkali metal ion as in an ammonium ferric ethylenediaminetetraacetate or a sodium ferric ethy-' lenediamine tetraacetate. Thebleach may also contain a non-chelated salt of an aminopolycarboxylicacid, e.g. the tetra sodium salt of ethylenediamine tetraacetic acid, inaddition to the ferric salt.

As is well known, the ferric complexes of these acids are generallysupplied inthe form of alkali metal or ammonium salts, e.g. sodiumferric ethylenediamine tetraacetic acid, ammonium ferric ethylenediaminetetraacetic acid, etc. Specifically preferred among these ma terials asthe bleaching agent is ammonium ferric ethylenediaminetetraacetic acidwhich has been found particularly useful in these formulations. I

While the above described silver vbleach solutions comprise the ironsalt silver bleaching agents, the iodide or bromide salts and thebromate salts, the bleach formulations ofthe invention may also includeother addenda which do not materiallyalter the fundamental silverbleaching and leuco dye conversion activities of the formulations. Forexample, compounds suchas uncomplexed aminopolycarboxylic acid,sulfites, bisulfites, acids (especially I-IBr) or buffers (especiallysodium acetate) (for pH control) etc. may be present. The concentrationof the ferric aminopolycarboxylic acid salts should be such thatbleaching proceeds relatively fast. About 10-400 grams/liter of theferric salt are useful. Unexpectedly, beyond about 400 grams/- literlevel, the bleaching rate decreases and recovery of silver from thesubsequent fixing treatment diminishes substantially. At ferric saltconcentrations below about 10 grams bleaching rates are extremely slow.

The bromide or iodide salt may be provided in the form of either thealkali metal or ammonium salt and is used in concentrations of fromabout 50-350 grams of bromide salt and about 1-350grams of iodide saltper liter.

According to a preferred embodiment of the present invention from about50 to about 300 grams/liter of bromide or iodide are used. Analternative embodiment which has also been found useful utilizes ableach which includes from about 50 to about 300 grams/liter bromidesalt and from about 1 to about 20 grams/liter of iodide salt.

The bromate may be supplied in any convenient salt form, i.e., as thealkali metal or ammonium salt, however, for reasons of solubility sodiumbromate has been found to be a particularly convenient and compatiblesource of this component.

As is demonstrated below, the pH of the bleach solution can be ofcritical importance insofar as the stability of the solution isconcerned. Thus, although useful bleach solutions can be obtained whenthe pH is maintained at between about 2.0 and 8.0, it is generally pre--ferred to maintain the pH of the bleach at about 4 to 6.5. Optimumresults are achieved at a pH of 5 i .5. At this last pH the stability ofthe bromate is increased considerably thereby increasing the useful lifeof the bleach Atpl-l levels below about 2 uantities of noxious gas aregenerally produced. At pH levels above about 8,.st b-s antia ly r19, lzsi hi spsu s The color processes with which the ferric salt bleachingsolutions are used include the well-known reversal subtractivecolorprocesses wherein multilayer color films and papers having couplercompounds in the emulsion layers are first developed with a black andwhite developer to form negative silver images in the layers. The filmis then generally developed with a pphenylenediamine type of colordeveloper containing a nucleating agent such as an amine borane compoundto form positive silver and dye images in the layers. Flash reversalexposure may of course also be used. Thereafter, the bleach solution ofthe invention is employed to form a silver salt soluble in fixingsolution. The film may be washed and/or may not, then fixed withthiosulfate fixing solution. As mentioned above, the silver can bereadily recovered from the fixing solution by' electrolytic means. Thebleach solutions containing the iron complexes can also be used inprocessing the color films to color negatives". In'this case, theexposed films are developed only in the color developer followed by thebleach solution of the invention and thiosulfate fixing solution toremove all silver from the film.

The following examples will serve to illustrate the invention.

An incorporated coupler multilayer color film is provided comprisingred, green and blue sensiti'vegelatinsilver halide emulsion layers on asupport, a yellow filter being coated between the blue and greensensitive emulsion layers. The emulsion layers'contain reactivemethylene and phenolic coupler compounds reactive withp-phenylenediamine developing agents to form dyes of colorscomplementary to the sensitivity of the respective layers. The film isexposed and-processed in sheet or roll form in a roller transport systemsuch as shown in Holley et al, Canadian Pat. No. 862,082 of Jan. 26,1971 at 85 F using the following steps:

Prehardener-3 minutes p-Toluene sulfinic acid (Na salt) 0.5 g. sulfuricacid (18 N) 5.41 ml. 2,5-dimethoxytetrahydrofuran 4.30 ml. sodiumsulfate, anhyd. 147.0 g. sodium bromide, anhyd. 2.0 g. sodium acetate,anh d. 20.0 g. formaldehyde (37.5 27.0 ml. n-methylbenzothiazoliump-toluene aulfonatc 0.04 g water to I liter Neutralizer 1 minuteHydroxylamine sulfate 18.0 g. sodium bromide, anhyd. 17.0 g. glacialacetic acid 10.0 ml. sodium hydroxide 6.8 g. sodium sulfate, anhyd. 50.0g. water to 1 liter First Developer 7 minutes sodium tetraphosphate 2.0g. n-methyl-p-aminophenol sulfate 5.0 g. sodium sulfite, anhydrous39.0'g. hydroquinone 6.0 g. sodium carbonate, monohydrate 24.0 g.potassium bromide 1.5 g sodium thiocyanate 1.32 g 0.1% solution ofpotassium iodide 9.0 cc water to l liter First Stop 2 minutes sodiumhydroxide 1.75 g. acetic acid, glacial 30.0 ml. water to 1 liter Wash 4minutes Color Developer 15 minutes benzyl alcohol 3.1 cc. sodiumtetraphosphate 5.0 g. sodium sulfite, anhydrous 7.6 g. trisodiumphosphate 12 B 0 36.0 g. potassium bromide 0.8 g. 0.1% solution ofpotassium iodide 28.0 cc. sodium hydroxide 2.0 g.4-arnino-N-ethyl-N-[B-methanesulfonamidoethyll-m-toluidine sesquisulfatemonohydrate lO.5 g. ethylenediamine 3.0 g, citrazinic acid 1.35 g.t-butylaminc borane 0.07 g. water to 1 liter Second Stop 2 minutessodium hydroxide 1.75 g. acetic acid, glacial 30.0 ml. water to 1 literWash 3 minutes Bleach 5 minutes potassium ferricyanide 165.0 g. sodiumbromide 43.0 g. water to 1 liter pH 8.70 t 0.15 (adjusted with NaOH orH,SO

Fix 6 minutes sodium thiosulfate (anhyd.) 94.5 g. sodium bisulfite(anhyd.) 17.6 g. disodium phosphate (anhyd.) 15.0 g. disodium salt ofethylenediaminetetraacetic acid 0.5 g

water to 1 liter adjust to pH 5.9

Wash 6 minutes Stabilizing Bat-h 1 minute polyoxyethylene ether alcohol(Col. 1 US. Pat. No. 3,369,896) O.l5 ml. formaldehyde (37.5%) 6.0 ml.water to l liter The results of red density measurements performed onthe processed film are shown in the FIGURE and described below. 1

treated as described in Example 1 except that the composition of thebleach was as follows:

Ammonium ferric ethylenediamine tetraacetate (58%) 300 ml. Ammoniumbromide 300 g. water to 1 liter pH 5.8 6.0 (adjusted with acetic acid)EXAMPLE 3 The method of Example 2 was repeated except that g/l of KBrOwas added to the bleach and the pH adjusted to 5i.5. n n The resultsof.red density measurements to show leuco dye formation are shown in theFIGURE and described below.

EXAMPLE 4 The method of Example 2 was repeated except that lOg/l of KBrOwere added to the bleachan dThe pH adjusted to 5 i .5.

The results of red density measurements to show the total lack of leucodye formation are shown in the FIG- URE and described below.

The FIGURE shows the red density of identical incorporated couplerreversal emulsions processed in identical photographic processingsolutions except that the composition of bleach was varied as describedin Example l-4 above.

The results shown in the FIGURE were obtained using conventionaldensitometric equipment and techniques.

As can be readily observed from these curves, curves 1 and 4 whichrepresent the standard ferricyanide bleach and the improvedaminopolycarboxylic acid, bromide. ion and bromate ion bleach of thepresent intions can be effected within the spirit and scope of theinvention.

We claim:

1. A photographic bleach composition comprising an aqueous solution offrom about 10 to about 400 grams per liter of a trivalent iron complexof an aminopolycarboxylic acid, a member selected from the groupconsisting of alkali metal and ammonium iodide and vention respectively,are superimposed, thus indicating that no leuco cyan dye was present inthe finished image.

Curve 2 which shows the red density of the same emulsion processed inthe same fashion as described in Examples 1 and 4 except that a bleachcornprising an aminopolycarboxylic acid and ammonium bromide and havinga pH of 6.0 was used, demonstrates substantial red density loss in theD-max region thus indicating the presence of rather substantial amountsof leuco cyan dye.

Curve 3 which shows the red density of an identical color reversalemulsion processed in the same manner as described in Example 2 exceptthat a small amount of potassium bromate was a dded to the bleach showsa minor loss in red density as compared to curves 1 and 4, but a rathersubstantial improvement in red density as compared to Example g, thusindicating that a reductioniii the amou nt of leuco cyan dye hasoccurred due to the presence of thebromate ion in the bleach.

The process of the above examples can be carried out so as to producecolor negative images in the emulsions by omitting the first developerstep and omitting the borane from the color developer. The other ferriccomplexes of the aminopolycarboxylic acids can be used in the bleachsolutions in a similar manner, the bleach solution also preferably beingacid if the ammonium ferric complex of the aminopolycarboxylic acids isused.

The invention has been described in detail with particular reference toa preferred embodiment thereof, but it will be understood thatvariations and modificabromide salts and mixtures of same, and fromabout 5 toabout 50 grams per liter of alkali metal or ammonium bromate,said solution having a pH of between about 2 and 8.

Y Y 2. The photographic bleach composition of claim 1 wherein theconcentration of said salt ranges from about I to about 350 grams perliter when said salt is an iodide salt and from about 5.0 to about 350grams per liter when said salt is a bromide salt.

3. The composition of claim 2 wherein said trivalent iron complex 'isselected from the group consisting of alkali metal and ammonium ferriccomplexes of an aminopolycarboxylic acid.

4. The composition of claim 3 wherein said trivalent iron complex is anammonium ferric ethylenediamine tetraacetate said bromate is sodiumbromate and the pH of said composition ranges from about 4 to.about.

.salt is ammonium bromide, said iodide salt is potassium iodide and thepH of said composition is about 5 i .5.

- 6. In a photographic color reproduction process wherein a plurality ofsuperposed differently sensitized silver halide emulsion layers aredeveloped with a p-phenylene-diamine developer to produce silver and dyeimages in the layers, the silver is bleached to form a silver complexsoluble in a fixing solution and the emulsion layers are fixed with afixing solution, the improvement comprising bleaching the silver with asolution comprising from about 10 to about 400 grams per liter of atrivalent iron complex of an aminopolycarboxylic acid, a member selected,from the group consisting of alkali metal and ammonium bromide andiodide salts and mixtures of said salts and from about 5 to about 50grams per liter of a member selected from the group consisting of alkalimetal and ammonium bromates, said bleach solution having a pH of between299! andfi.

7. The process according to claim 6 wherein the concentration of saidsalt ranges from about l to about 350 grams per liter when said salt isan iodide salt and from about 50 to about 350 grams per liter whensaidsalt is a bromide salt.

8. The process according to claim 7 wherein the trivalent iron complexis selected from the group consisting of alkali metal and ammoniumferric complexes of an aminopolycarboxylic acid.

9. The process according to claim 7 wherein the 11. The processaccording to claim 10 wherein said trivalent iron complex -is anammonium ferric ethylenediamine tetraacetate said bromate is sodium.brornate and the pH of said bleach solution ranges from about 4 toabout 6.5.

12. The process according to claim 11 wherein said bromide salt isammonium bromide, said iodide salt is potassium iodide and the pH ofsaid bleach solution is about 5 i.5.

* i t t I?

2. The photographic bleach composition of claim 1 wherein theconcentration of said salt ranges from about 1 to about 350 grams perliter when said salt is an iodide salt and from about 50 to about 350grams per liter when said salt is a bromide salt.
 3. The composition ofclaim 2 wherein said trivalent iron complex is selected from the groupconsisting of alkali metal and ammonium ferric complexes of anaminopolycarboxylic acid.
 4. The composition of claim 3 wherein saidtrivalent iron complex is an ammonium ferric ethylenediaminetetraacetate said bromate is sodium bromate and the pH of saidcomposition ranges from about 4 to about 6.5.
 5. The composition ofclaim 4 wherein said bromide salt is ammonium bromide, said iodide saltis potassium iodide and the pH of said composition is about 5 + or - .5.6. In a photographic color reproduction process wherein a plurality ofsuperposed differently sensitized silver halide emulsion layers aredeveloped with a p-phenylene-diamine developer to produce silver and dyeimages in the layers, the silver is bleached to form a silver complexsoluble in a fixing solution and the emulsion layers are fixed with afixing solution, the improvement comprising bleaching the silver with asolution comprising from about 10 to about 400 grams per liter of atrivalent iron complex of an aminopoly-carboxylic acid, a memberselected from the group consisting of alkali metal and ammonium bromideand iodide salts and mixtures of said salts and from about 5 to about 50grams per liter of a member selected from the group consisting of alkalimetal and ammonium bromates, said bleach solution having a pH of betweenabout 2 and
 8. 7. The process according to claim 6 wherein theconcentration of said salt ranges from about 1 to about 350 grams perliter when said salt is an iodide salt and from about 50 to about 350grams per liter when said salt is a bromide salt.
 8. The processaccording to claim 7 wherein the trivalent iron complex is selected fromthe group consisting of alkali metal and ammonium ferric complexes of anaminopolycarboxylic acid.
 9. The process according to claim 7 whereinthe emulsion layers in a color reversal process are first developed witha black and white developer and then with color developer prior tobleaching the silver with the trivalent iron complex.
 10. The processaccording to claim 7 wherein said trivalent iron complex is selectedfrom the group consisting of sodium and ammonium ferric ethylenediaminetetraacetate.
 11. The process according to claim 10 wherein saidtrivalent iron complex is an ammonium ferric ethylenediaminetetraacetate said bromate is sodium bromate and the pH of said bleachsolution ranges from about 4 to about 6.5.
 12. The process according toclaim 11 wherein said bromide salt is ammonium bromide, said iodide saltis potassium iodide and the pH of said bleach solution is about 5 + or -.5.